Laboratory processing of liquids requires the transport thereof through flow lines connecting vessels disposed at various levels. The liquids involved must be moved at determined flow rates, and they must not be contaminated. In practice, there are infinite arrangements of the apparatus involved and pumping is often required as an adaptation to transport a wide variety of liquids. For example, such liquids are electrophoresis buffers, sea water, cell suspensions, biological liquids, coolants, and any number of plating solutions, and the like. Accordingly, the pump herein disclosed is fabricated of materials unaffected by the liquid substance transported thereby, and such that it can be assembled without the complications of threads and/or solvent welds, the elements thereof being formed of plastic such as polyvinylchloride or a polytetrafluoroethylene polymer such as Teflon as manufactured by Dupont and which is substantially inert. These elements are simple and of open formation for cleanliness and for observation and priming of the pumping action, centrifugal action being employed through an impeller operating in a chamber isolated from the prime mover drive, utilizing a magnetic coupling. Reference is made to the prior art stirrers wherein a drive table provides a magnetic field that rotates and which is followed by magnetic stirring bars that are free to revolve within a closely positioned vessel in which liquid is to be agitated. It is a general object of this invention to employ such a stirrer table, as will be described, to drive a laboratory pump superimposed thereon and operable to be primed and operated with facility and under observation.
Pumps of the type under consideration are usually shaft driven and involve closed chambers and seals. Metallic bearings, shafts and impellers are usually employed, and access requires tedious disassembly. Furthermore, visibility of the pumping action is not available, and priming must be accomplished by improvision outside the pump. Accordingly, it is an object of this invention to eliminate closed inaccessible chambers, to eliminate all metallic parts, shafts and seals, and to provide in place thereof non-magnetic plastic parts adapted to visible inspection of the pumping function during operation and all of which are easily disassembled for installation modification and/or cleaning. A feature is the self priming of this pump with its integral priming chamber.
Drive tables of the type under consideration are common for use in stirring liquids within vessels superimposed thereon, and are referred to generally as "magnetic stirrers". It is an object of this invention to combine such a stirrer, without change thereto, with a liquid transporting pump especially adapted to laboratory use. The alignment of stirring bars within a vessel is not critical, but the alignment of a magnetic field rotating concentric with a pump drive axis is obviously a problem. However, criticality of this pump drive alignment is obviated by the present invention wherein the pump impeller seeks equilibrium within a wide range of misalignment with the axis of the drive table, precise alignment being impractical. With the present invention, the pump impeller is essentially a free spinning "top" stabilized gyroscopically in equilibrium with the magnetic drive axis even when axially offset, within practical limits. Further, the self alignment feature involves the inherent centering force of the magnetic attraction which tends to align the impeller and pump per se centered with the axis of the drive table.